Follistatin-344: research

Human gene-therapy findings do not establish a dose for follistatin-344 protein vials.

Also called: FS344, FST344, FS-344, Follistatin 344.

Myostatin pathway · Myostatin- and activin-binding protein precursor.

Gene-vector administration is separate from direct protein exposure. Registrations do not establish results. A protein-injection evidence level is not established here.

Studies

Follistatin-344 dosage

Typical reported dose: 100 mcg once a day

  • Reported 100 mcg daily course: 100 mcg daily daily, under the skin. Reported by users, rare report. Studied in: Adults discussing self-use for muscle growth. (source)
  • Same log, intramuscular use: 100 mcg daily after changing route daily, into muscle. Reported by users, rare report. Studied in: Adults discussing self-use for muscle growth. (source)
  • Circulating daily range: 100–200 mcg daily for 10–30 days daily, under the skin. Reported by users, rare report. Studied in: Adults discussing self-use for muscle growth. (source)
  • Circulating training-day schedule: 50 mcg on training days on training days only, into muscle. Reported by users, rare report. Studied in: Adults discussing self-use for muscle growth. (source)
  • Whole-vial exposure in eye cases: Adverse-event exposure in a retrospective eye-clinic case series: complete 1 mg vials injected subcutaneously; not an established treatment regimen. one reported injection; repeats varied, under the skin. Reported by users, rare report. Studied in: Eleven male bodybuilding athletes presenting with central serous chorioretinopathy after self-directed injections. (source)

These are doses reported in labels, trials or user reports, not a personal plan. Check the source behind each one.

Work out syringe units with the dosing calculator

Follistatin-344 side effects and risks

Reported side effects

  • Retinal fluid leakage and blurred vision: 11 selected eye cases after reported 1 mg injections; user wide incidence unknown., serious. Stop injections and seek urgent eye assessment for new blur, distortion or a dark spot. (source)
  • Injection pain, swelling and fever-like symptoms: Reported in one self use log; no reliable rate., moderate. Stop further exposure and seek assessment for marked swelling, persistent fever or worsening pain. (source)
  • Immune reactions or contaminants: Human rates are unknown; market testing found wrong proteins and manufacturing tags., serious. Breathing trouble or facial swelling needs emergency care. (source)
  • Reproductive-hormone effects: Activin binding creates a mechanistic concern; human protein injection risk is unknown., moderate. Review fertility plans and menstrual or sexual changes with a clinician. (source)
  • Raised LDL after plasmid gene delivery: Unreviewed 43 person manuscript reports mean LDL +11.6 mg/dL at three months., moderate. This gene-therapy finding cannot be assigned to protein-vial use. (source)

Stop and get help if

  • New blurred or distorted vision, or a central dark spot: Stop injections and get urgent eye care today.
  • Breathing trouble, fainting, or swelling of the face or tongue: Call emergency services now; stop further exposure.
  • Fever with a hot, expanding injection-site swelling or severe pain: Stop injections and get urgent medical assessment.

Who should avoid it

  • pregnant: No pregnancy safety data for protein injections; gene-therapy trials exclude pregnancy.
  • breastfeeding: No infant-exposure or breastfeeding safety data; excluded in the current AAV trial.
  • tryingToConceive: Activin affects reproductive signaling; safe fertility exposure and washout are unknown.
  • under18: Adult self-use protocols exclude minors; three pediatric gene-transfer cases do not establish protein-injection safety.
  • activeCancer: Current gene-therapy trial excludes active or recent cancer. Protein effects on cancer growth are unresolved.
  • cancerHistory: Recent cancer is excluded from current gene-therapy research; long-term recurrence risk is unknown.
  • other: Reported high-dose use is linked to retinal fluid leakage; avoid further exposure with active or prior disease.
  • liverDisease: Human protein dosing in liver disease is unstudied; gene-transfer studies monitor liver tests.
  • kidneyDisease: Dose changes in kidney disease are unknown; gene-transfer studies monitor kidney function.
  • immunosuppressed: Product sterility and immune risks are unresolved; AAV studies require specialized immune screening.
  • surgeryPlanned: No perioperative safety or validated washout for protein injections was found.
  • testedAthlete: Follistatin is prohibited at all times under WADA S4.3; gene transfer may also fall under M3.

Interactions

  • Corticosteroids: Both exposures are linked to retinal fluid leakage. Additive risk is a precaution; no combination trial exists.
  • Other myostatin or activin blockers: Overlapping growth-signal blockade has unknown combined risks. No human trial supports stacking these products.
  • Growth hormone and IGF products: Discussed together for muscle gain; no human trial establishes safety or added benefit with injected follistatin.

Product quality risks

  • Only 9/17 tested products contained follistatin; all nine had His-tags and many protein oligomers.
  • Other tested products contained growth-related peptides such as MGF or GHRP-2.
  • The label does not establish identity, amount, biological activity, sterility or endotoxin safety.

How Follistatin-344 works

Follistatin binds myostatin and activin, signals that normally limit muscle growth. FS344 is a gene-encoded precursor that becomes circulating FS315 after processing. Gene therapy makes cells produce protein; a vial injection has different exposure and risks.

  • Myostatin / GDF-8: Binding prevents a signal that limits muscle growth.
  • Activins: Binding also affects signals involved in reproduction and other tissues.

Half-life: Human half-life of injected follistatin-344 protein is unknown.

Gaps: No controlled dose-finding, efficacy or pharmacokinetic trial of community follistatin-344 protein injections was found. Gene therapy, plasmid DNA and recombinant protein have different dose units, exposure and risks. Human protein-injection pregnancy, breastfeeding, fertility, immune and long-term cancer risks remain unknown. Three early unilateral myositis patients lack a separate full outcome report; registry and publication cohort wording differs. Myositis walking benefits are disputed and confounded by prednisone, exercise and unequal follow-up. The 43-person plasmid manuscript is uncontrolled and unreviewed; no registry results are posted. The 14-person combination trial and recruiting AAV9 trial have no posted results. No validated protein-vial reconstitution, shelf life or safe repeat-cycle interval was found. Community prevalence is unmeasured; guide circulation is not proof of common completed use. No compound-specific poison-center series or current representative market survey was located. The evidence level includes related gene-therapy studies and observed protein exposure; it does not indicate a validated protein protocol.

Related to Follistatin-344

Follistatin-344: the short version

Sources

Sources checked: 2026-10-18.

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